A security policy is a formal document that outlines the rules, procedures, and guidelines an organization follows to protect its information, systems, and networks from security threats. It defines what employees and users can and cannot do, how data should be handled, and the measures in place to prevent unauthorized access or data breaches. Security policies help ensure that everyone in the organization understands their responsibilities in maintaining security and provide a framework for responding to incidents. They are regularly updated to address new risks and comply with legal or industry standards.